In the pending application of Daniel M. Cap and William H. Lake, Ser. No. 812,479, filed July 5, 1977, entitled High Pressure Metal Vapor Discharge Lamps Improved in Efficiency and assigned like this application, new miniature discharge lamps having envelope volumes of about 1 cubic centimeter or less are disclosed. These lamps have ratings starting at about 100 watts and going down to less than 10 watts, and characteristics including life-durations making them suitable for general lighting purposes. They are wall-stabilized and may utilize fillings comprising mercury and metal halides. In them the input wattage is reduced, while ratios of arc watts to electrode watts similar to those in larger sizes of lamps are maintained by increasing the mercury vapor pressure at the same time as the discharge volume is decreased. In larger conventional sizes of lamps, convective instability of the arc sets a limit on mercury vapor pressure. But by going to a small envelope, one cubic centimeter in volume or less, it becomes possible to increase mercury vapor pressure severalfold while yet avoiding convective instability. However it is necessary to maintain the desired electrode temperature with the reduced energy input, and that must be achieved primarily by reducing the physical size of the electrodes and inleads in order to reduce the heat loss from them.